Conveyors may be used in stackers to stack material or reclaim material from a stack. Typically, systems designed for stacking and reclaiming material utilize a number of conveyors. One set of conveyors is typically used to convey material to a stacker for stacking in a particular area. Another set of conveyors is used to reclaim the material stacked in that area. Examples of systems used to stack material or reclaim material are disclosed in U.S. Pat. Nos. 6,782,993, 6,085,890, and 3,604,757, and U.S. Patent Application Publication No. 2007/0102263, and World Intellectual Property Organization Publication No. WO2008/138418.
In addition to conveyors, other devices are typically used in stacking and reclamation systems. For instance, a stacker is typically used to stack material transported by the stacking conveyor system. A reclaimer, such as a bucket wheel reclaimer, may be used for reclaiming the stacked material and placing that material on a reclaimer conveyor. Examples of stackers and reclaimers are disclosed in U.S. Pat. Nos. 3,297,141, 3,653,486, 4,406,361, 4,629,060, 6,360,876, and 6,896,123.
One previous system used for stacking material included using radial stackers and grasshopper conveyors. The radial stacker in such systems is configured to work in a circular path and often has an extendable conveyor head to increase the stacker's stacking capacity. Once the radial stacker completed its rotation at a first location, the head of the stacker may be extended and the stacker could reverse its path to further stack material. After the stacker had finished stacking the material at the first location, the stacker would need to be moved to a new location to stack material at the new location or new portion of a predefined area for stacking material. Such movement often takes a significant amount of time. For instance, the stacker may need to be moved by a lifting device or by moving the stacker. Also, additional extension conveyors would need to be added to a system to extend the material flow to the stacker. Such movement requires the system to be shut down during each movement of the stacker. Further, there are wasted corners in the stacking of the material that the circular path of the radial stacker cannot utilize such that several thousand tons of capacity in a stacking area may be not be utilized. Moreover, a separate set of conveyors is typically needed to reclaim material off the stacked pile, which can make such systems very expensive.
Another previous system can use a racetrack system similar to leach pad stacking. The racetrack system typically uses a mobile stacking bridge conveyor, a mobile reclaim conveyor, a bucket wheel reclaimer, a central corridor feed overland conveyor and a corridor reclaim overland conveyor. The feed and reclaim overland conveyors may run parallel, but in different directions. Such a system often requires the blending of reclaimed material into a circuit of conveyors. In the event there are different materials to be stacked, the mobile reclaim or mobile stacking conveyor must be moved in a complex path that requires movement between different piles of material. Such movement is often time consuming and requires multiple complex pivots. Moreover, such movement requires a substantial mount of space for performing movement between different material piles so the amount of space that may be utilized for stacking can be significantly minimized or underutilized. Such systems can also require very complex site layouts that include tunnels for the mobile conveyors to travel over the corridor conveyors when stacking or reclaiming. Further, such a stacking and reclaiming system cannot stack or reclaim during the movement of the conveyors.
A system for stacking and reclaiming is needed that provides for the utilization of more space for stacking. Such a system should also provide for as simple a site layout as possible for the stacking and reclaiming of material. Preferably, such a system is configured to decrease the amount of time the stacking or reclaiming needs to be stopped for adjustment or movement of stacking or reclaiming devices such as stackers, bucket wheels or conveyors.